DE102015110961B4 - Inspection system - Google Patents

Abstract

An inspection system for monitoring a battery of a vehicle (10), comprising:an array (24) of battery cells (26) arranged along an axis A; andan inspection aid comprising:a label (30) attached to the surface (32) of a metal casing of each battery cell (26) for monitoring the temperature and internal pressure of the battery cells (26), having a temperature sensitive portion indicating temperature changes, and a load-sensitive section with a plurality of reference points that indicates position changes, characterized in that the inspection system further comprises a controller (38) and an optical device (34), a first of the plurality of the reference points being spaced a distance from a second of the plurality of reference points, wherein the distance increases in response to increasing pressure within a battery cell (26) and the distance decreases in response to decreasing pressure in the battery cell (26), and wherein the controller (38) is configured by the optical device (34) during optical reading of the label recorded information about temperature change and position of reference points using the distance to calculate the load on the area of the battery cell (26) near the label (30), the controller operatively using a database (42) of reference colors and the with temperatures associated with those colors and can execute an image recognition/processing program that compares the color revealed in the scan of the label (30) with the reference colors contained in the database (42) to determine the temperature.

Description

GENERAL STATE OF THE ART

Electrified vehicles use electric machines for propulsion. Electric vehicles, hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs) are exemplary types of electric vehicles.

Batteries power the electrical machines. Inspecting, maintaining and replacing batteries and other components is sometimes necessary. Various factors impact decisions to initiate additional inspections, maintenance, or component replacement.

In print US 2002/0 119 364 A1 discloses that the internal pressure of a battery cell can be monitored using a label attached to the battery cell that includes a load-sensitive portion that indicates relative position changes. The label contains a metallic film and is arranged around the battery cell. Another method for measuring the internal pressure using a sensor is described in the publication US 2013 / 0 093 383 A1 disclosed.

In print US 2006 / 0 008 699 A1 A temperature indicator for a battery cell is described. This is arranged over the entire outside of the battery cell.

The publications form further prior art in the background of the invention US 7,477,995 B2 , US 2009 / 0 192 731 A1 and WO 2013/112 531 A2 .

BRIEF PRESENTATION OF THE INVENTION

An inspection aid includes, among other things, a label with a temperature sensitive section that indicates temperature changes and a stress sensitive section that indicates position changes.

In another non-limiting embodiment of the above inspection aid, the temperature sensitive portion includes a thermochromic material that changes color in response to temperature changes.

In a further, non-limiting embodiment of one of the above inspection aids, the thermochromic material comprises a thermochromic ink.

In a further non-limiting embodiment of any of the above inspection aids, the stress sensitive portion includes a plurality of reference coordinates that move relative to one another in response to expansion or contraction of the label.

In a further, non-limiting embodiment of one of the above inspection aids, a first of the plurality of reference points is spaced at a distance from a second of the plurality of reference points. The distance increases in response to increasing pressure within a battery. The distance decreases in response to the decreasing pressure within the battery. Alternatively, certain permanent increases in distance are also possible as a result of plastic deformation after exposure to high pressure.

In a further, non-limiting embodiment of one of the above inspection aids, the device includes an identification portion of the label. The identification section contains identification information.

In a further non-limiting embodiment of one of the above inspection aids, the identification section provides at least a part of the temperature-sensitive section and at least a part of the stress-sensitive section.

In a further, non-limiting embodiment of one of the above inspection aids, the identification section comprises a bar code.

In a further, non-limiting embodiment of one of the above inspection aids, the identification section comprises a QR (Quick Response) code.

The label is attached to a battery cell.

A method of inspecting a battery according to an exemplary aspect of the present invention includes, among other things, detecting changes in a temperature of a battery from a temperature-sensitive portion of a label, and detecting changes in load on the battery from a load-sensitive portion of the label.

In another non-limiting embodiment of the above method, changes in a color of the temperature sensitive portion indicate a change in temperature.

In a further non-limiting embodiment of any of the above methods, the load-sensitive portion includes reference coordinates, and a change in the relative position of the reference coordinates indicates a change in the load.

In a further non-limiting embodiment of any of the above methods, the method includes optically reading the label to collect color and position.

In a further non-limiting embodiment of any of the above methods, a distance between at least some of the reference coordinates that increases with time indicates more stress and a distance between at least some of the reference coordinates that decreases with time indicates less stress.

In a further non-limiting embodiment of any of the above methods, the method includes estimating pressure within the battery using the load.

In a further non-limiting embodiment of any of the above methods, the method further includes collecting identification information about the battery during optical reading of an information portion of the label.

In another non-limiting embodiment of any of the above methods, the method includes directly securing the label to the battery.

In a further non-limiting embodiment of any of the above methods, the method includes painting the label directly onto the battery.

In a further non-limiting embodiment of any of the above methods, the method includes referencing a database while detecting, the database comprising at least one reference color associated with at least one of a temperature, a measurement of stress associated with a pressure, or both.

In a further non-limiting embodiment of any of the above methods, the method includes updating the database using information from while detecting.

In a further non-limiting embodiment of any of the above methods, the method includes diagnosing that a battery should be replaced based on changes in temperature, changes in load, or both.

The embodiments, examples and alternatives of the preceding paragraphs, the claims or the following description and the drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment may be applied to all embodiments unless such features are incompatible.

DESCRIPTION OF THE FIGURES

• 1 veranschaulicht eine schematische Ansicht eines beispielhaften Elektrofahrzeugs.
• 2 veranschaulicht eine Perspektivansicht einer optischen Einrichtung, die Batteriezellen aus einem Batteriepaket des Elektrofahrzeugs von 1 inspiziert.
• 3 veranschaulicht eine vergrößerte Seitenansicht einer der Batteriezellen von 2, die ein Etikett gemäß einer Ausführungsform der vorliegenden Offenbarung zeigt.
• 4A veranschaulicht ein Etikett, das in einem weiteren Ausführungsbeispiel an einer Batteriezelle angebracht ist.
• 4B veranschaulicht das Etikett von 4A, nachdem die Batteriezelle sich relativ zu der Batteriezelle von 4A erwärmt hat und ausgedehnt hat.

The various features and advantages of the disclosed examples will become apparent to those skilled in the art from the detailed description. The figures that accompany the detailed description can be briefly described as follows:

• 1 illustrates a schematic view of an example electric vehicle.
• 2 illustrates a perspective view of an optical device that contains battery cells from a battery pack of the electric vehicle 1 inspected.
• 3 illustrates an enlarged side view of one of the battery cells of 2 , showing a label according to an embodiment of the present disclosure.
• 4A illustrates a label attached to a battery cell in another embodiment.
• 4B illustrates the label of 4A , after the battery cell moves relative to the battery cell 4A warmed and expanded.

DETAILED DESCRIPTION

The present disclosure relates generally to inspecting and diagnosing components and, more particularly, to monitoring variables such as the temperature and internal pressure of a battery cell. The present disclosure involves monitoring these variables using a common label.

With reference to 1 An exemplary electric vehicle 10 contains a battery pack 14 for powering an electrical machine 18. The vehicle contains wheels 22 that are driven by the electrical machine 18. The electric machine 18 receives electrical power from the battery pack 14 and converts the electrical power into torque.

The exemplary vehicle 10 is a fully electric vehicle. In other examples, the vehicle 10 is a hybrid electric vehicle that selectively drives wheels using an internal combustion engine instead of or in addition to the electric machine 18. In hybrid-electric examples, the electric machine 18 may selectively operate as a generator to recharge the battery pack 14.

Now with reference to the 2 and 3 The battery pack 14 contains an array 24 of battery cells 26 which are arranged along an axis A. The battery cells 26 may be axially compressed by end walls not shown, other components such as side walls, and covers may surround other sides of the battery cells 26. In some embodiments, the battery pack 14 may contain 50 to 500 individual battery cells 26 within the array 24. In other examples, the battery pack 14 may contain only a single cell. The cells in this example are lithium-ion cells.

A label 30 is attached to an outward-facing surface 32 of each of the battery cells 26. The exemplary label 30 generally includes an information section, a temperature-sensitive section, and a stress-sensitive section. The temperature sensitive section may include the stress sensitive section and vice versa. The temperature sensitive portion, the stress sensitive portion, or both could also be used as part of the identification portion of the label 30.

The label 30 is a type of inspection aid or diagnostic tool. The label 30 is adhesively attached to the surface 32 of the battery cell 26. Surface 32 is typically part of a metal casing (or bag) of the battery cell. The label 30 may be a single unitary structure or a collection of individual separate components.

In this example, an optical device 34 such as a digital camera may optically scan the label using lasers, charge coupled device (CCD) imagers, active pixel sensors, or other types of optical detection or sensing techniques.

At least a portion of the exemplary label 30 includes a matrix code, such as a bar code, representing data relating to, among other things, a serial number of the battery cell 26 to which the label 30 is attached. The barcode can be a stacked barcode, a straight barcode, etc.

The matrix code is a type of identification section, and the bar code is a type of matrix code. In other examples, the identification section is another type of matrix code such as an Aztec Code, DateGlyph, Data Matrix, MaxiCode, Qode or Shotcode.

Scanning the label 30 allows a user to collect the data represented by the bar code. A controller 38 collects the data represented by the bar code. The data can be compiled by the controller 38 to be viewed on a display, a printout, etc.

The bar code of the label 30 may instead or additionally represent data relating to the battery pack 14, the vehicle 10, or both. Other exemplary data represented by the barcode includes the date of manufacture for the battery cell 26, the manufacturing location, and other types of data useful for identifying characteristics of the battery cell 26 and surrounding structures.

In the exemplary label 30, the temperature sensitive portion is a thermochromic material such as a thermochromic ink. The thermochromic material changes color in response to temperature. For purposes of this disclosure, a change in color may refer to the image color as well as a change in hue.

While scanning the label 30, the optical device 34 detects a color of the temperature-sensitive portion of the label 30. The detected color is compared to a reference color to determine a temperature of the label.

The exemplary controller 38 is operatively connected to a database 42 of reference colors and the temperatures associated with those colors. In some examples, scanning the label initiates access to a database that is online. A reference or baseline label image may be associated with the barcode in the database 42.

The controller 38 may execute an image recognition/processing program that compares the color revealed in the scan of the label 30 with the reference colors contained in the database 42 to determine the temperature. The image recognition/processing program can be run either by the controller or on a server be executed. The controller 38 may use image recognition software to assist in the comparison.

In some examples, database 42 also stores a color and temperature history of label 30 and associated battery cell 26. As label 30 is repeatedly scanned throughout the life of battery cell 26, the detected colors and their temperatures are stored in database 42.

A color difference between a color detected in one scan and a color detected in a previous scan indicates a change in temperature. Because the label 30 is attached directly to the surface 32, the temperature change can be viewed as a temperature change of the surface 32 and more generally a temperature change of the battery cell 26. Thus, scans of the label by the optical device 34 may reveal a temperature of the battery cell 26.

In some examples, the thermochromic material changes color as the temperature fluctuates. Thus, the thermochromic material represents a temperature at a time of scanning by the optical device 34.

In other examples, the thermochromic material changes color permanently after reaching a certain temperature. That is, the change in color remains even if the temperature of the battery cell 26 decreases from that temperature.

For example, the thermochromic material of the label 30 may change from black to red if the label 30 is exposed to temperatures above 150°F. The thermochromic material is designed such that the red color remains even if the temperature decreases from 150°F. A subsequent scan of the label 30 by the optical device 34 would then reveal that the battery cell 26 and the associated label 30 have experienced temperatures above the threshold temperature of 150°F, even if their current temperature were significantly below 150°F. Identifying whether the battery cell 26 has ever reached a certain temperature can be helpful when evaluating maintenance requirements.

In addition to the information portion and the temperature sensitive portion, the label 30 additionally includes the stress sensitive portion including the first line 46a and the second line 46b as reference positions. Changes in the relative or absolute positions of the first line 46a and the second line 46b can be used to determine the stress across the surface 32.

For example, the first line 46a is spaced from the second line 46b by a distance D. Internal pressure within the battery cell 26 causes the battery cell 26 to swell. As can be understood, this increases the distance D. The exemplary optical device 34 measures the distance D during scanning. The distance D is communicated to the controller 38.

The controller 38 calculates the load on the area of the battery cell 26 near the label 30 using the measurement of the distance D. The levels of the load may be calculated using actual changes in length at distance D, changes in aspect ratios, etc.

The measurement of the load across the surface 32 can be correlated with the current pressure within the battery cell 26 or a previous pressure within the battery cell 26. These correlations can be stored and accessed by the database 42. Both tensile and compressive loads can be correlated with an increase in pressure depending on the location of the label, i.e. the cell may "contract" in some locations, such as near edges, as pressure increases.

A technician may rely on test results in a laboratory to develop the specific levels of stress corresponding to a specific internal pressure within the battery cell 26. The controller 38 determines an estimated internal pressure within the battery cell 26 using the measurement of the load. The levels of the load corresponding to the determined internal pressure can be stored within the database 42.

In general, the stress ε is a dimensionless number indicating relative deformation resulting from a stress field induced by applied forces or pressure or due to changes in the temperature field within the body. The loading can occur in any direction of a coordinate system and can be monitored by the displacement of reference points such as lines 46a and 46b.

In this example, changes in the distance D with respect to the specified initial conditions are read optically in order to evaluate the physical state of the object to be monitored, here the battery cell 26. This means that reference color and position information can be used during the optical reading of the label 30 can be collected.

In some examples where multiple relative or absolute reference point changes in multiple different directions can be used to characterize the direction and magnitude of the load. Alternatively, the ratios of relative or absolute changes in different directions can be used to characterize the direction and magnitude of the load. Furthermore, a specific or preferred direction may also be chosen on the basis that it provides better correlation with pressure for calibration purposes.

Persons responsible for maintaining the battery pack 14 may periodically scan the label 30 and the labels 30' of other battery cells within the array 24. This information is saved within the controller's database 42. Significant changes in monitored temperatures, load, or both may prompt the technician to replace one or more of the battery cells 26. In addition to collecting information about the cell from a database (e.g. on a website, cloud server), the newly collected information from the label 30 about temperature, stress or pressure history can be uploaded to the database 42 for future reference and comparison.

Although the label 30 is described for use in conjunction with battery cells 26, those skilled in the art can, with the benefit of this disclosure, understand other items that would benefit from the label 30. For example, the disclosure could be used to monitor other items that are sensitive to heat, pressure, or stress, such as structural parts in aircraft, components of boilers and pressure vessels, etc.

Now with reference to the 4A and 4B Another exemplary label 40 is printed with a matrix code such as a QR (Quick Response) code instead of a straight barcode. The label 40 includes thermochromic ink printed on a surface 44 of a battery cell 26. The thermochromic ink provides the thermochromic portion of the label 40. Color changes in the thermochromic ink indicate temperature changes. In this example, label 40 is in the vicinity of 4B at a significantly higher temperature and a different color than label 40.

The label 40 also has a stress-sensitive section. Within the label 40, the reference points are represented by geometric patterns such as a first point 50a, a second point 50b and a third point 50c. An optical device scanning the label 40 may provide information to the controller 38 that determines the distance and relative positions of the first point 50a, the second point 50b and the third point 50c. These measurements reveal changes in position of the points that can be used to determine the pressure or pressure history within a battery cell.

In this example, the distances between the first point 50a, the second point 50b and the third point 50c for the label 40 are in the vicinity of 4B larger than the label of 4A . This means that the surface 44 is in the vicinity of 4B is more heavily loaded than the surface 44 in the area 4A and that the internal pressure of the battery cell 26 is in the vicinity of 4A is greater than the internal pressure of the battery cells 26 in the area of 4B .

Features of this disclosure include a label that provides both temperature and pressure information about a battery cell. Collecting this information from the same label reduces inspection time, diagnostic time, costs and errors. Collection may include calibration to reflect changes in internal pressure as a function of measured stress along specific directions.

The pressure and temperature information measured by the label, or the history of this information, along with relatively rapid access to a database containing baseline information, can provide a rapid and reliable diagnostic tool for monitoring the health of battery cells or pressure/temperature sensitive items. In some examples, the temperature, stress and pressure history may be simultaneously uploaded to an online server for processing against previous data and/or for future reference.

The foregoing description is exemplary rather than restrictive in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art, which do not necessarily depart from the spirit of this disclosure. Thus, the extent of legal protection afforded to this disclosure can only be determined by reading the following claims.

Claims (9)

An inspection system for monitoring a battery of a vehicle (10), comprising: an array (24) of battery cells (26) arranged along an axis A; and an inspection aid comprising: a label (30) for monitoring the temperature and internal pressure of the battery cells (26) attached to the surface (32) of a metal casing of each battery cell (26) with a temperature sensitive portion indicating temperature changes, and a load-sensitive section with a plurality of reference points that indicates position changes, characterized in that the inspection system further comprises a controller (38) and an optical device (34), a first of the plurality of the reference points being spaced a distance from a second of the plurality of reference points , wherein the distance increases in response to increasing pressure within a battery cell (26) and the distance decreases in response to decreasing pressure in the battery cell (26), and wherein the controller (38) is configured by the optical device (34 ) information recorded during the optical reading of the label about temperature change and position of reference points using the distance to calculate the load on the area of the battery cell (26) near the label (30), the controller operating with a database (42) of reference colors and the temperatures associated with those colors and can execute an image recognition/processing program that compares the color revealed in the scan of the label (30) with the reference colors contained in the database (42) to determine the temperature. inspection system Claim 1 , wherein the temperature-sensitive portion comprises a thermochromic material that changes color in response to temperature changes. inspection system Claim 2 , wherein the thermochromic material comprises a thermochromic printing ink, and the thermochromic material permanently changes color after reaching a certain temperature. Inspection system according to one of the Claims 1 until 3 , wherein the stress-sensitive portion includes a plurality of reference coordinates that move relative to one another in response to expansion or contraction of the label (30). Inspection system according to one of the Claims 1 until 4 , further comprising an identification section of the label (30), the identification section containing identification information. inspection system Claim 5 , wherein the identification section provides at least a part of the temperature-sensitive section and at least a part of the load-sensitive section. inspection system Claim 5 , wherein the identification section comprises a barcode. inspection system Claim 5 , wherein the identification section includes a QR (Quick Response) code. Inspection system according to one of the Claims 1 until 8th , wherein the label (30) is printed on a lithium-ion battery cell.

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